抄録
A water-recirculating system instead of a conventional flow-through system was studied for the reason that experimental water which was recirculating in an aquarium.during the fish in-festivity trials fbr IPN virus (IPNV) can be completely disinfected by a small amount of chlorlne.The required numbers of fish for an aquarium and of aquaria for an experiment in the water-recirculating system developed was determined. Fish and virus used in this study were rainbow trout fry (Salmo gairdneri, 0.11-0.14g in B. W.) and IPNV-Buhl. Fish were exposed to 105_0 TCID50/ml of IPNV and incubated for 28 days at 15°C. The experiments revealed the fol-lowing facts: Twenty-five fish per aquarium were required as a minimum. In the case of ap-proximately 35-70% in cumulative mortatities, 2, 4and approximately 8 aquaria per experiment were required respectively when 90%of all the experimental values occupied the mean ±15(%), ±10(%)and±5(%). In the case of approximately 90%in cumulativc mortalities, 2 aquariaper experiment were required when approximately 95%of all the experimental values occupied the mean±5(%).
